Renewable fuse



Sept. 4, 1934. MlLLER 1,972,569

RENEWABLE FUSE Filed May 2, 1952 7 2 N fla, Q13 14 0 29 fi Z6 Z7 5 5 Z5 E //v VENTOB. DA V/D MILLER Patented Sept. 4, 1934 gTA'f'ES PAT T @FFHQE 7 (Jlaims.

My invention relates to an improved construction of renewable fuses for electrical work, by which I provide a fuse member of simple and cheap construction which can readily be placed in position in the fuse structure, and I also provide an improved indicating means for definitely showing when a fuse is blown, which indicating means comprises an electric lamp contained in the fuse structure, which is lighted when the fuse 0 member is blown. The lamp bulb employed may be of any desired type, for example, it may be a neon bulb or a similar bulb having spaced electrodes, or it may be a bulb of the usual lighting variety having a continuous filament. In this manner, I am able to positively indicate which one or ones of a group of fuses are blown, the indication being clearly visible at a distance from the fuses, so that there is no need to closely examine any of the fuse structures, in the event of a fuse or fuses being blown, which saves time in replacing the blown fuse or fuses with fresh ones. Inasmuch as the lamp bulb employed in the fuse structure is lighted only when the fuse element is blown, the lamp bulb is of very long life and need not be replaced. Thus the indica ing devices employed not only have the advantage of being clearly visible without close inspection of the fuses, but in addition they are permanent and require no replacement.

By my invention I thus provide a renewable fuse structure aifording positive indication of the blowing of the fuse member, and in addition, a structure in which the only part that needs to be replaced in the event of the blowing of a fuse, is a fuse member of very simple and inexpensive construction, which fuse member can be put in place in the fuse structure simply and correctly by anyone, whether familiar with electrical or mechanical devices or not.

My improved fuse construction is applicable to fuses of many types, including fuses of the screw plug type and cartridge fuses.

My invention will best be understood by reference to the accompanying drawing showing a 4 preferred embodiment thereof, in which Fig. 1 illustrates to an enlarged scale, in central, longitudinal, sectional view, a fuse of the screw plug type embodying my invention,

Fig. 2 is a sectional view of the structure shown in Fig. 1 taken along theline 2-2, and in this figure I also show the fuse member and fuse clamping disk separate from the main fuse structure,

Fig. 3 illustrates in longitudinal, sectional View,

a cartridge fuse embodying my invention, and

(Cl. 2G0-121) Fig. 4 illustrates diagrammatically the connections employed with an indicating lamp bulb of the continuous filament type, as distinguished from indicating lamp bulbs of the neon type shown in Figs. 1 and 3. 6

Similar numerals refer to similar parts throughout the several views.

The fuse construction shown in Fig. 1, consists of a cylindrical body portion 10 of molded insulating material, carrying on its inner end portion, a thin metal shell 11 having a threaded formation to lit in a standard electrical socket of the threaded variety. The inner end of the shell 11 is flanged over the end of the body portion 10, as shown at 11a. The inner end wall of the body portion 10 has secured in it a metal block or nut 12 to receive a screw 13, which screw extends centrally through a clamping disk 14 of insulating material, and also through the inner end of a fusible member 15 which is of suitable fuse alloy in thin sheet form and provided with an aperture at its inner end through which the screw 13 extends. The fusible member 15 is of a length to rest against the outer surface of the flange 11a and substantially in line with the outer edge of the disk 14, the disk 14 being preferably slightly smaller as to its outer diameter, than the diameter of the shell 11 at the bottom of its threads. The screw 13 thus serves to clamp the fusible member 15 against the block or nut 12 at one end of said member, and against the flange 11a of the shell 11, at the other end of said member, the screw 13 in addition serving as one terminal of the fuse structure. The nut 12 and flange 11a are insulated and spaced from each other, depending upon 9Q the voltage with which the fuse structure is to be used.

The body portion 10 is hollow and contains a lamp bulb 16 which may be of any desired type, the bulb illustrated being of the neon type, and supported in the body portion 10 in any suitable manner, for example, by strips 17 of insulating material. Where the lamp bulb is of the neon type, a high resistance or leak is used in circuit with the bulb, such leak being indicated at 18 as supported by the strips 17, 17. One terminal of the bulb 16 is connected by a wire 19 with the shell 11, the other terminal of said bulb being connected by a wire 20 with one terminal of the leak 18, the other terminal of said leak being connected by wire 21 with the nut 12. As a result of this construction, when the fusible member is intact, there is no appreciable electrical potential impressed upon the terminals of the lamp bulb 16. When however, the fusible member is blown, substantially the full electrical potential of the circuit is impressed on the terminals 11 and 13 of the fuse structure and so through the leak 18, on the terminals of the lamp bulb 16, which is thereupon lighted, regardless of the electrical devices that may at the time be in circuit with the fuse structure, on account of the amount of current required to illuminate the bulb 16 being very small. The outer end wall of the body portion 10 is provided with a sight aperture in which a metal sleeve or grommet 22 is mounted to support a light transmitting disk 23, for example of mica, so that the illumination of the bulb 16 may be clearly seen from the outer end of the fuse structure. The disk 23 may conveniently be supported imposition by forming an inwardly extending bead 22a on the sleeve 22 to constitute a seat for the disk 23, and placing a split spring ring 2% in the sleeve 22 to hold the disk upon said seat. The illumination of the bulb 16 is thus clearly apparent from the outer end of the fuse structure, and at a considerable distance therefrom, without closely examining the fuse structure in any way, and when any one of a group of fuses is blown, it can at once be identified and removed without the loss of time incident to determining which fuse is blown by taking out one fuse after another, as is necessary where no positive indicating devices are provided.

It will be understood that the lamp bulb 16 and leak 18 may be supported in the body portion 10 in any other manner desired, for example by filling material of any convenient type, the supporting structure described beingmerely illustrative of one means for accomplishing this result.

In Fig. 3, I illustratethe embodiment of my in vention in a fuse of the cartridge type. In this construction, a tubular and cylindrical body portion 10a of insulating material is employed having metal end walls or plugs 25 and 26 tightly secured in the body portion and provided with central threaded apertures to receive screws 27 and 28 respectively, which screws also extend centrally through metal end ferrules 29 and 30 held in place on the ends of the body portion 1011 by said screws, the fit of said'ferrules on the body portion being such that they may'readily be removed from the body portion when desired, said ferrules constituting the connecting terminals of the cartridge fuse. A lamp bulb 16a is mounted in the body portion 10a and held in place in any convenient manner, for example by strips 17a, 17a of insulating material, and where the lamp bulb 16a is of the neon type, as illustrated in Fig; 3 a high resistance or leak 18a may also be conveniently supported in the body portion 1011 by said strips 17a, 17a. One of the terminals of the bulb 16a is connected by wire 31 with theplug 25 and the other terminal of said bulb is connected by wire 32 with one terminal of the leak 18a, the other terminal of which is connected by wire 33 with the other end plug 26. The end plugs 25 and 26, and the strips 17.a,17a are provided with aligned apertures permitting the ready'insertion of a fusible member 15a of a length to extend through the end plugs .25 and 26, with its ends bent against the outer surfaces of said plugs, in which position the end portions of the fusible memberare securely clamped by the screws 27 and 28 between the end plugs and the ferrules 29 and 30. The side wall of the body portion 10a is provided with a sight aperture 34 preferably closed 'loy a thickness of light transmitting material 35, for example mica, so that when the bulb 16a is lighted, it will give a positive indication of its lighted condition through the sight aperture 34, the operation of the bulb 16a being the same as above described for the construction shown in Fig. 1. It will be understood that the bulb 16a and leak 18a may be supported in any other convenient manner in the tubular portion 10a of the fuse, for example by suitable filling material, since the means shown in Fig. 3 for supporting the bulb and leak are illustrative only of one means that may be used to accomplish this result. With the construction shown in Fig. 3, when the fusible member 15a is blown, all that is required torenew it, is to remove the ferrules 29 and 30, insert a new fusible member through the aligned apertures in the end plugs 25 and 26 and in the strips 17a, 17a, and replace the ferrules 29 and 30 and secure them in position by the screws 27 and 23 to clamp the ends of the fusible member in place. This construction has all of the advantages above described for the construction shown in Fig. l, the only difference being that it is adapted for other purposes and uses than is the construction illustrated in Fig. 1.

In Fig. 4 I illustrate diagrammatically the circuit connections employed where the lamp bulb is of the continuous filament type. In 'thisfigure, I illustrate the use of the bulb with the type of construction shown in Fig. 1 and show a threaded metal shell 11?) and a spaced contact block 121), which block is connected by a wire 36 with one of the terminals of the bulblfib, the other terminal of which bulb is connected by a wire 37 with its the shell 11b, the remaining parts of the structure being the same as above described in connection with Fig. 1. It is obvious that similarzchanges may be made in the electrical connections of the structure shown in Fig. 3 where it is desired to use in connection with that structure, a lamp bulb of the continuous filament type.

From the above it will be observed that by my invention I provide a means for affording a visi ble light signal for indicating the blowing, of fuses of different types which, it will be understood, is applicable to many different types of fuse structures and to many different forms of fusible members, and that I also provide an improved construction of renewable fusible members which is inexpensive and may readily be inserted in fuse structures of different kinds.

While I have shown my invention in the particular embodiment abovedescribed, it will be understood that I do not limit myself to this ex act construction as I may employ equivalents known to the art at the time of the filing of this application without'departing from the scope of the appended claims. 1

What I claim is:

ii o

1. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, a screw extending through saiddisk and into said nut and clamping said fusible member in place against said nut andsaid flange, said body portion being hollow and having .a sight aperture in its outer end, a lamp bulb in said body portion'and having its terminals electrically connected with said shell and said nut, and a light transmitting closure for said sight aperture.

2. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange, said body por tion being hollow and having a sight aperture in its outer end, a lamp bulb in said body portion and having its terminals electrically connected with said shell and said nut, and a light transmitting closure for said sight aperture, said fusible member comprising a thin flat piece of fusible material having a perforation at one end to receive said screw.

3. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange, said body portion being hollow and having a sight aperture in its outer end, and a lamp bulb in said body portion and having its terminals electrically connected with said shell and said nut.

4. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange, said body portion being hollow and having a sight aperture in its outer end, a lamp bulb of the neon type in said body portion and having its terminals electrically connected with said shell and said nut, a light transmitting closure for said sight aperture, and a high resistance leak in said body portion in said bulb connections.

5. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, and a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange.

6. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, and a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange, said fusible member comprising a thin flat piece of fusible material having a perforation at one end to receive said screw.

7. In a fuse, the combination of a body portion of insulating material, a threaded metal shell on said body portion having a flange overlapping the inner end of said body portion, a metal nut in the inner end of said body portion, a disk of insulating material, a fusible member between the inner end of said body portion and said disk and extending from said nut to said flange, a screw extending through said disk and into said nut and clamping said fusible member in place against said nut and said flange, and indicating means visible by current flowing therethrough and actuated by blowing of said fusible member.

DAVID MILLER. 

